CN110312484B

CN110312484B - Tandem bar connector and related method

Info

Publication number: CN110312484B
Application number: CN201880011232.3A
Authority: CN
Inventors: J.迪塞尔曼; K.李; J.R.霍金斯; R.卡露斯
Original assignee: Medos International SARL
Current assignee: Medos International SARL
Priority date: 2017-02-10
Filing date: 2018-02-06
Publication date: 2023-02-03
Anticipated expiration: 2038-02-06
Also published as: US20210068872A1; JP2020507400A; US11793554B2; JP7106554B2; US20240023998A1; AU2018218225A1; AU2018218225B2; US20190175226A1; US10238432B2; EP3579770B1; US10869695B2; CN110312484A; US20180228518A1; WO2018148193A2; EP3579770A2; WO2018148193A3

Abstract

Disclosed herein are connectors that can be used to attach a rod to a bone anchor assembly that has been occupied by a separate rod. Various ways of attaching the connector to the bone anchor assembly are disclosed, including locking the connector to the bone anchor in an arrangement, constraining the connector in one or more degrees of freedom relative to the bone anchor in an arrangement, adjusting the connector in one or more degrees of freedom relative to the bone anchor in an arrangement, and including a spherical articulation joint in an arrangement. In some embodiments, attachment of the connector to the bone anchor may be aided by the use of a positioner. The geometry of the connector is selected to minimize the offset between the first rod received in the bone anchor assembly and the second rod received in the connector.

Description

Tandem bar connector and related method

Technical Field

Orthopedic devices and methods are disclosed herein, including tandem rod connectors and related methods.

Background

Fixation systems may be used in orthopedic surgery to align and/or fix a desired relationship between two or more bones or bone segments. For example, in spinal surgery, spinal fixation systems may be used to align and/or fix a desired relationship between vertebrae. Typical spinal fixation systems may include bone screws or other anchors implanted into the vertebrae and connected by a longitudinal rod.

There may be situations where it is desirable or necessary to arrange a plurality of rods in series. For example, the rods may be arranged in series when adding rods to an existing construct to extend the construct to additional vertebral levels, or when seeking to achieve rod offsets to clear other implants or patient anatomy, or to better fit a series of implanted bone anchors. There are also situations where it is desirable or necessary to attach multiple rods to the same bone anchor. This may occur, for example, when insufficient space or poor bone quality prevents the initial use of a separate bone anchor in a particular location, or prevents the use of a connector that is directly attached to both rods. Existing solutions for attaching multiple rods may be awkward, may require large offsets between the rods, or may limit the flexibility with which one rod may be positioned relative to another.

Accordingly, there is a need for an improved rod connector and associated methods.

Disclosure of Invention

Disclosed herein are connectors that can be used to attach a rod to a bone anchor assembly that has been occupied by a separate rod. Various ways of attaching the connector to the bone anchor assembly are disclosed, including locking the connector to the bone anchor in an arrangement, constraining the connector in one or more degrees of freedom relative to the bone anchor in an arrangement, adjusting the connector in one or more degrees of freedom relative to the bone anchor in an arrangement, and including a spherical articulation joint in an arrangement. In some embodiments, attachment of the connector to the bone anchor may be aided by the use of a positioner. The geometry of the connector may be selected to minimize the offset between a first rod received in the bone anchor assembly and a second rod received in the connector, for example, using angled or curved rod grooves and/or fasteners or set screws that are offset from the center of the rod or angled relative to the bone anchor. The connector may be configured to align the first and second rods in a common coronal plane, or may be configured to position one rod more anterior or more posterior than the other rod.

In some embodiments, a connector assembly may include a connector having a proximal end and a distal end defining a proximal-distal axis, the connector comprising: a first portion configured to mate the connector with a receiver member of a bone anchor assembly having a first rod receiving recess for receiving a first rod; and a second portion, wherein a second rod receiving groove is formed in the second portion, the second rod receiving groove configured to receive a second rod; a first fastener having a distal portion configured to engage the receiver member to lock the first rod to the receiver member and a proximal portion extending through an opening formed in the first portion of the connector; a nut engageable with the fastener to secure the connector to the receiver member; and a second fastener engaged with the second portion of the connector to lock the second rod to the connector; wherein the second rod receiving recess comprises a proximal opening and a distal seat, and wherein the proximal opening is offset from the distal seat in a direction perpendicular to the proximal-distal axis.

The first and second rods may have a rod diameter, the first and second rods may have a center-to-center offset when seated in the receiver member and the connector, respectively, and the ratio of the center-to-center offset to rod diameter may be in the range of about 2. The ratio of the center-to-center offset to the rod diameter may be about 2. The center-to-center offset of the first and second rods may be in the range of about 6mm to about 16mm, for example, in the range of about 6mm to about 10mm, when the first and second rods are seated in the receiver member and the connector, respectively. The center-to-center offset of the first rod and the second rod may be about 8mm when the first rod and the second rod are seated in the receiver member and the connector, respectively. The first rod receiving recess may include a first rod seat, and the first rod seat may be distal to the seat of the second rod receiving recess. The first rod receiving recess may include a first rod seat, and the first rod seat may be proximal to the seat of the second rod receiving recess. The first rod receiving recess may include a first rod seat, and the first rod seat may be at substantially the same proximal-distal height as the seat of the second rod receiving recess.

The first portion of the connector may include a groove configured to receive a proximal end of the receiver member, the groove being cylindrical such that the receiver member is free to rotate relative to the connector about a central axis of the receiver member when the receiver member is received in the groove. The first portion of the connector may include a groove configured to receive a proximal end of the receiver member, the groove including one or more flats that abut corresponding flats of the receiver member such that when the receiver member is received in the groove, the receiver member is constrained to uniplanar motion relative to the connector. The first portion of the connector may include a groove configured to receive a proximal end of the receiver member, the groove forming a substantial negative of the receiver member such that the receiver member cannot rotate or translate relative to the connector when the receiver member is received in the groove. The portion of the connector may include a domed, proximally facing distal surface that bears against a proximally facing surface of the receiver member in the gimbal interface. The opening in the first portion of the connector is oversized relative to the first fastener to allow movement of the connector relative to the receiver member. The assembly can include a locator having a central opening that receives the first fastener therein and a distally extending tab that engages the receiver member to limit rotation between the locator and the receiver member.

The locator may include teeth configured to selectively engage with the teeth of the connector to limit rotation between the connector and the receiver member. The retainer may include a flat formed on an outer sidewall of the retainer and configured to selectively engage a flat formed on an inner sidewall of the connector to limit rotation between the connector and the receiver member. Tightening the nut is effective to clamp the tabs of the retainer to the fastener. The nut may have a spherical outer surface that is received within a spherical inner surface of the opening formed in the first portion of the connector to allow polyaxial movement of the connector relative to the receiver member. The nut may include a tapered distally facing surface that contacts a tapered proximally facing surface of the connector. The tapered surfaces of the nut and the connector may taper at different angles to each other. The tapered surfaces of the nut and the connector may taper at the same angle. The nut may be a locking nut configured to expand within the opening to lock an orientation of the connector relative to the receiver member.

At least one of the first fastener and the through bore of the lock nut has a tapered thread such that rotation of the lock nut relative to the first fastener is effective to radially expand the lock nut. The locking nut may have a slotted drive feature with a curved abutment surface. A distal surface of the connector may be configured to constrain movement of the connector relative to the receiver member to a direction parallel to the first rod. A distal surface of the connector may be configured to constrain movement of the connector relative to the receiver member to a direction perpendicular to the first rod. The second rod may be positionable in the second rod receiving recess by moving the second rod distally relative to the connector. The second rod receiving recess may follow a curved path between the proximal opening and the distal socket.

The second rod receiving recess may follow a path that is obliquely angled relative to the proximal-distal axis of the connector. The axis of rotation of the second fastener does not intersect the central longitudinal axis of the second rod when the second rod is seated in the connector. The rotational axis of the second fastener may extend at an oblique angle relative to the proximal-distal axis of the connector. The second fastener may be a set screw and the set screw may be received within a set screw recess formed in the connector, a center of the set screw recess may be offset from a center of the proximal opening of the second rod receiving recess in a direction perpendicular to the proximal-distal axis. The distal seat of the second rod receiving recess defines a V-shape configured to receive rods of different diameters. The assembly may include a bone anchor assembly, the first rod, and the second rod.

In some embodiments, a connector assembly may include a connector including an opening defining a spherical inner surface and a rod-receiving groove laterally offset from the opening and configured to receive an elongated spinal rod; a threaded fastener; and a locking nut received within the opening of the connector, the locking nut having a spherical outer surface and a threaded through bore in which a proximal end of the fastener is received; wherein the assembly has an unlocked configuration in which the connector is polyaxially movable relative to the fastener and a locked configuration; in the locked configuration, the orientation of the connector relative to the fastener is fixed, and the locking nut is radially extended in the locked configuration as compared to the unlocked configuration.

The threads of the fastener or the threads of the lock nut are tapered such that rotation of the lock nut relative to the fastener is effective to radially expand the lock nut. The locking nut may have a grooved drive feature with a curved abutment surface. The distal surface of the connector may include a first planar portion and a second planar portion oriented at an oblique angle relative to the first planar portion to constrain movement of the connector relative to a receiver member in which the set screw is disposed.

In some embodiments, a method of spinal fixation can comprise: implanting a bone anchor assembly into a vertebra of a patient, the bone anchor assembly including a receiver member having a first rod receiving recess; inserting a first rod into the first rod-receiving groove of the receiver member; inserting a first fastener into the receiver member to secure the first rod in the receiver member; positioning a connector over the receiver member such that a proximal portion of the first fastener extends through an opening formed in the connector; inserting a second rod into a second rod receiving groove formed in the connector; inserting a second fastener into a fastener groove formed in the connector to secure the second rod in the connector; adjusting an orientation of the connector relative to the receiver member to achieve a desired positioning of the first and second rods; and tightening a nut on the fastener to fix the orientation of the connector relative to the receiver member.

The method may include positioning the first rod and the second rod such that a center-to-center offset between the first rod and the second rod is in a range of about 6mm to about 16mm, for example, in a range of about 6mm to about 10 mm. The method may include positioning the first and second rods such that a ratio of the center-to-center offset between the first and second rods to the diameter of the first and second rods is in a range of about 2. The method may include positioning the first rod and the second rod such that a ratio of a center-to-center offset between the first rod and the second rod to a diameter of the first rod and the second rod is about 2. The method can include placing a locator between the connector and the receiver member, wherein the locator limits relative rotation between the connector and the receiver member about the first fastener after the nut is tightened. The method may include positioning the first rod and the second rod such that the first rod precedes the second rod. The method may include positioning the first and second rods such that the first and second rods lie substantially in a common coronal plane. Inserting the second rod may include moving the rod distally and laterally within the curved rod receiving groove. Inserting the second rod may include moving the rod distally and laterally within the obliquely angled rod-receiving recess. Inserting the second rod may include top loading the rod into the connector. Adjusting the orientation may include pivoting the connector about at least one of a uniplanar interface, a gimbal interface, and a spherical articulation joint.

Drawings

The following detailed description is provided with reference to the accompanying drawings, in which:

FIG. 1A is a perspective view of a connector assembly shown with a bone anchor and first and second rods;

FIG. 1B is an exploded perspective view of the connector assembly and bone anchor of FIG. 1A;

FIG. 1C is a top view of a connector of the connector assembly of FIG. 1A;

FIG. 1D is a cross-sectional side view of the connector of FIG. 1C;

FIG. 1E is a perspective view of the connector assembly, bone anchor and rod of FIG. 1A secured to a patient's vertebrae;

FIG. 2A is an exploded perspective view of the connector assembly with a spherical articulation joint and shown with a bone anchor;

FIG. 2B is a cross-sectional side view of the connector assembly and bone anchor of FIG. 2A;

FIG. 2C is a cross-sectional side view of the lock nut of the connector assembly of FIG. 2A;

FIG. 2D is a top view of the locking nut of FIG. 2C;

FIG. 2E is a bottom view of the locking nut of FIG. 2C;

FIG. 3A is a partial perspective view of a connector assembly having a spherical articulation joint and shown with a bone anchor;

FIG. 3B is a partial cross-sectional side view of the connector assembly of FIG. 3A;

FIG. 3C is a top view of the connector assembly and bone anchor of FIG. 3A;

FIG. 3D is a partial side view of the connector assembly and bone anchor of FIG. 3A;

FIG. 4A is a cross-sectional side view of a connector having a gimbal interface;

FIG. 4B is an end view of the connector of FIG. 4A shown with a bone anchor;

FIG. 4C is a top view of the connector of FIG. 4A;

FIG. 5A is a side view of the connector having a sidewall for constraining movement of the connector relative to the bone anchor;

FIG. 5B is an end view of the connector of FIG. 5A;

FIG. 5C is a bottom view of the connector having a recess for restraining movement of the connector relative to the bone anchor;

FIG. 6A is an exploded perspective view of the connector assembly shown with a bone anchor and rod;

FIG. 6B is a cross-sectional end view of the connector and retainer of the connector assembly of FIG. 6A;

FIG. 6C is a bottom view of the connector of FIG. 6A;

FIG. 6D is a top view of the fixture of FIG. 6A;

FIG. 7A is an exploded perspective view of the connector assembly shown with a bone anchor and rod;

FIG. 7B is an assembled perspective view of the connector assembly, bone anchor and rod of FIG. 7A;

FIG. 7C is a perspective view of a retainer of the assembly of FIG. 7A;

FIG. 7D is a side view of the retainer of FIG. 7C;

FIG. 7E is a top view of the positioner of FIG. 7C;

FIG. 7F is a bottom view of the retainer of FIG. 7C;

FIG. 7G is a perspective view of a connector of the assembly of FIG. 7A;

FIG. 7H is a partial bottom view of the connector of FIG. 7G;

FIG. 7I is a partial bottom view of the connector and retainer of FIG. 7A in a first configuration;

FIG. 7J is a partial bottom view of the connector and retainer of FIG. 7A in a second configuration;

FIG. 7K is a partial bottom view of the connector and retainer of FIG. 7A in a third configuration;

FIG. 7L is a cross-sectional end view of the connector assembly, bone anchor and rod of FIG. 7A;

FIG. 8 is a side view of the connector assembly shown with a bone anchor and first and second rods;

FIG. 9A is a perspective view of the connector assembly shown with a bone anchor and first and second rods;

FIG. 9B is a perspective view of a connector of the connector assembly of FIG. 9A;

FIG. 9C is a cross-sectional side view of the connector of FIG. 9B;

FIG. 10A is a side view of a connector having an angled rod receiving groove; and is provided with

Fig. 10B is a side view of a connector having a V-shaped lever seat.

Detailed Description

Disclosed herein are connectors that can be used to attach a rod to a bone anchor assembly that has been occupied by a separate rod. Various ways of attaching the connector to the bone anchor assembly are disclosed, including locking the connector to the bone anchor in an arrangement, constraining the connector in one or more degrees of freedom relative to the bone anchor in an arrangement, adjusting the connector in one or more degrees of freedom relative to the bone anchor in an arrangement, and including a spherical articulation joint in an arrangement. In some embodiments, attachment of the connector to the bone anchor may be aided by the use of a positioner. The geometry of the connector can be selected to minimize the offset between a first rod received in the bone anchor assembly and a second rod received in the connector, for example, using angled or curved rod grooves and/or fasteners or set screws that are offset from the center of the rod or angled relative to the bone anchor. The connector may be configured to align the first and second rods in a common coronal plane, or may be configured to position one rod more anterior or more posterior than the other rod.

Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. Features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments.

Fig. 1A-1E illustrate an exemplary embodiment of a connector assembly 100, which connector assembly 100 may be used, for example, to connect a second spinal rod 107 to a bone anchor assembly 101 in which a first spinal rod 106 is received. The connector assembly 100 may include a connector 130 having a first portion 140 for mating the connector with the bone anchor assembly 101 and a second portion 150 for mating the connector with a fixation element, such as the illustrated rod 107. As described further below, the first portion 140 of the connector 130 may receive the head of the bone anchor assembly 101 or the proximal portion 104p of the receiver member 104, nest on the proximal portion 104p, or otherwise interact with the proximal portion 104 p. The connector 130 may be attached to the receiver member 104 in various ways, for example using a first fastener or set screw 108 and a nut 132 as shown in fig. 1A-1B. The set screw 108 may include a distal portion 108d received in the receiver member 104 and a proximal portion 108p that extends through an opening 142 in the connector 130 and to which the nut 132 may be threaded. The nut 132 may be tightened to lock the connector 130 relative to the receiver member 104. The second portion 150 of the connector 130 may be disposed adjacent to the first portion 140. The second portion 150 may include a rod-receiving groove or channel 152 sized and configured to receive the spinal rod 107 therein. A second fastener (set screw or other closure mechanism) 134 may be secured within the proximal opening 156 of the second portion 150 of the connector 130 to lock the spinal rod 107 therein. Although a second set screw and a second set screw are shown, other fasteners, such as quarter-turn closure caps, nuts, or the like, may alternatively or additionally be used.

An exemplary bone anchor assembly 101 is shown in fig. 1A-1B and described below, but it should be understood that the connector assembly 100 may be used with any of a variety of bone anchor assemblies. Other exemplary bone anchor assemblies and associated features are disclosed in U.S. patent No. 6,736,820, issued 5/18/2004, U.S. patent No. 6,974,460, issued 12/13/2005, U.S. patent No. 7,179,261, issued 2/20/2007, 2015, U.S. patent No. 9,155,580, issued 2/23/2016, and U.S. patent No. 9,433,445, issued 9/6/2016, each of which is incorporated herein by reference in its entirety. The illustrated bone anchor assembly 101 generally includes a proximal head or receiver member 104 and a threaded distal shank or bone anchor 102. Bone anchor 102 may be integrally formed with receiver member 104 or may be a separate component that is movably coupled to the receiver member. In the latter configuration, bone anchor 102 may be selectively locked in any of a variety of orientations relative to receiver member 104. For example, prior to locking, the bone anchor 102 may be moved polyaxially relative to the receiver member 104 within an angled cone generally defined by the geometry of the distal end of the receiver member and the proximal head of the bone anchor. The bone anchor assembly 101 may be locked to maintain the bone anchor 102 in a fixed orientation relative to the receiver member 104. The bone anchor assembly 101 may be a favored-angle screw, a conventional (non-offset) polyaxial screw, a monoaxial screw, a uniplanar screw, a hook, or any of a variety of other bone anchor types known in the art.

A first fixation element or rod 106 may be received within the receiver member 104. The first rod 106 may directly contact the proximal head of the bone anchor 102 or may contact an intermediate element such as a compression cap or collet (not shown). For example, a compression member may be positioned within receiver member 104 and interposed between spinal rod 106 and the proximal head of bone anchor 102 to compress the distal outer surface of the proximal head into direct fixed engagement with the distal inner surface of receiver member 104. Receiver member 104 may include a central longitudinal axis or proximal-distal axis A1. The receiver member 104 may include a pair of spaced apart arms 114A, 114B defining a first rod receiving groove or channel 120 for receiving the spinal rod 106. The channel 120 may be U-shaped as shown, or may have various other configurations. The rod 106 seated in the channel 120 may have a central longitudinal axis A3 that is perpendicular to the axis A1 of the receiver member 104.

In the illustrated embodiment, the first rod 106 is an elongated cylindrical spinal rod, but it should be understood that the rod may take other forms, such as a bone plate, wire, tether, etc. Although the first rod 106 is shown as having a circular cross-section, any of a variety of cross-sections may be used, such as oval, rectangular, square, rectangular, triangular, hexagonal, and so forth. The first rod 106 may have any of a variety of diameters. In some embodiments, the diameter may be in the range of about 2.5mm to about 7.5mm. For example, the diameter may be about 2.5mm, about 3.0mm, about 3.5mm, about 4.0mm, about 4.5mm, about 5.0mm, about 5.5mm, about 6.0mm, about 6.5mm, about 7.0mm, or about 7.5mm. The first rod 106 may be substantially straight along its length, or may include one or more bends or curves formed therein. The first rod 106 may be malleable or bendable such that it can be bent before or during the procedure to achieve the desired correction.

The proximal end of the channel 120 formed in the receiver member 104 may be configured to receive a closure mechanism 108 that may be positioned between and engage the arms 114A, 114B of the receiver member. A closure mechanism 108 is selectively securable to the receiver member 104 to capture a spinal fixation element (e.g., spinal rod 106) within the receiver member. Tightening or locking the closure mechanism 108 may effectively fix the first rod 106 relative to the receiver member 104 and fix the angular position of the bone anchor 102 relative to the receiver member 104. The illustrated closure mechanism 108 is in the form of a threaded post having an increased diameter distal portion 108d and a reduced diameter proximal portion 108p. In other embodiments, the proximal portion 108p and the distal portion 108d may have the same diameter, or the proximal portion may have a diameter that is greater than the diameter of the distal portion. The distal portion 108d of the closure mechanism 108 may be threaded into the receiver member 104 to engage the first rod 106 disposed in the receiver member 104. The proximal portion 108p of the closure mechanism 108 may protrude above the receiver member 104 (e.g., above a proximal-facing terminal surface of the receiver member) and pass through an opening 142 formed in the connector 130, as described further below.

In the illustrated embodiment, the closure mechanism 108 bears directly against the spinal rod 106, which spinal rod 106 in turn bears directly against the head of the bone anchor 102. However, it should be understood that one or more intermediate elements may also be included in the bone anchor assembly 101. For example, the bone anchor assembly 101 may include a compression member disposed between the spinal rod 106 and the head of the bone anchor 102. The closure mechanism 108 may be a single set screw as shown, or may include an outer set screw operable to act on the compression member and an inner set screw operable to act on the rod 106. Independent locking of (i) the orientation of bone anchor 102 relative to receiver member 104 and (ii) rod 106 relative to receiver member 104 can be achieved using internal and external set screws. The closure mechanism 108 may include a drive interface 109 (e.g., star, flat, cross-head, square, or other) to facilitate rotational advancement or retraction of the closure mechanism relative to the receiver member 104 using a drive instrument.

As mentioned above, the connector 130 may include a first portion 140 and a second portion 150. The first portion 140 may have a proximal-facing surface 140p and a distal-facing surface 140d. As shown in fig. 1C, the first portion 140 can include a through-hole 142 extending from the proximal-facing surface 140p to the distal-facing surface 140d. For example, the through-hole 142 is sized to receive the proximal portion 108p of the set screw 108 therethrough. As shown in fig. 1D, the through-hole 142 may have a central longitudinal axis A5. The axis A5 may be collinear or substantially collinear with the longitudinal axis A1 when the connector 130 is mounted on the receiver member 104, or may be offset or obliquely angled relative to the axis A1. Set screw 108 may be inserted through-hole 142 of connector 130 to allow the connector to sit on receiver member 104, e.g., on a proximal-facing end surface of the receiver member.

The first portion 140 of the connector 130 may include various geometries or features for interacting with the receiver member 104. For example, as shown in fig. 1D, first portion 140 can define a groove 144, the groove 144 sized to receive at least a portion of receiver member 104 therein. The groove 144 can be defined by an annular or substantially annular sidewall 145 extending distally from the distal-facing surface 140d. As described further below with respect to fig. 4A-5C, the geometry of the groove 144 may be selected to constrain movement of the connector 130 relative to the receiver member 104 in one or more degrees of freedom, or to allow adjustment of the connector 130 relative to the receiver member 104 in one or more degrees of freedom. In the embodiment shown in fig. 1D, the inner surface 146 of the sidewall 145 is cylindrical or substantially cylindrical, which can allow the connector 130 to rotate relative to the receiver member 104 about the axis A5 when the receiver member is disposed in the groove 144 (e.g., when the proximal-facing end surface of the receiver member is seated against the distal-facing surface 140D of the connector).

The sidewall 145 may form a negative of at least a portion of the receiver member 104. For example, the inner surface 146 may form a negative of the curved outer sidewall portion of the receiver member 104 such that the connector 130 may surround the receiver member 104 with minimal or zero clearance therebetween. For example, inner surface 146 may be concave with a radius of curvature equal to or substantially equal to the radius of curvature of the exterior sidewall of receiver member 104.

With the proximal portion 108 of the set screw 108p inserted through the opening 142 in the connector 130, the nut 132 may be threaded onto the set screw 108 to secure the connector 130 to the receiver member 104. When tightened, the nut 132 may lock the position and orientation of the connector 130 relative to the receiver member 104. The position of the connector 130 may be adjusted prior to tightening the nut 132 to achieve a desired orientation of the second rod 107 relative to the first rod 106. The nut 132 may include a distally facing surface configured to mate with a proximally facing surface 140p of the connector 130. For example, the proximal facing surface 140p of the connector 130 may have a dome or spherical shape, and the distal facing surface of the nut 132 may have a corresponding dome or spherical shape. Such an arrangement may facilitate locking of the connector 130 to the receiver member 104 when the connector is angled or pivoted relative to the receiver member, as described further below. The nut 132 and the proximal facing surface 140p of the connector may mate in a manner described further below with respect to the corresponding components of fig. 7A-7L.

The second portion 150 of the connector 130 may define a second rod receiving groove or channel 152 for receiving the second rod 107 therein. The assembly 100 can be configured such that when the first and

second rods

106, 107 are received therein, the longitudinal axes A3, A4 of the

rods

106, 107 are offset from one another in one or more planes (e.g., in the coronal plane, in the sagittal plane, or in both the coronal and sagittal planes of the patient). It is understood that the diameter of the first rod 106 may be smaller, equal, or larger than the diameter of the second rod 107. As shown, second rod 107 is an elongated cylindrical spinal rod, but it should be understood that second rod 107, like first rod 106, may take other forms, such as a bone plate, wire, tether, etc. It should also be understood that while the second rod 107 is shown as having a circular cross-section, any of a variety of cross-sections (such as oval, oblong, square, rectangular, triangular, hexagonal, etc.) may be used. The second rod 107 may have any of a variety of diameters. In some embodiments, the diameter of the second stem 107 may be in the range of about 2.5mm to about 7.5mm. For example, the diameter of the second stem 107 may be about 2.5mm, about 3.0mm, about 3.5mm, about 4.0mm, about 4.5mm, about 5.0mm, about 5.5mm, about 6.0mm, about 6.5mm, about 7.0mm, or about 7.5mm. Second rod 107 may be substantially straight along its length, or may include one or more bends or curves formed therein. The second rod 107 may be malleable or bendable such that it may be bent before or during the procedure to achieve the desired correction. The rod 107 seated in the channel 152 may have a central longitudinal axis A4.

The second rod receiving groove 152 may be defined by opposing first and

second arms

152a, 152 b. As shown, the first portion 140 of the connector 130 may be a cantilevered lateral extension of the first arm 152 a. Second rod receiving groove 152 may be open in a proximal direction such that rod 107 may be inserted into the groove by moving the rod distally relative to connector 130. Each of the

arms

152a, 152b can include features (not shown) such as grooves, dimples, notches, protrusions, and the like, to facilitate coupling the connector 130 to various instruments. For example, the outer surface of each

arm

152a, 152b can include an arcuate slot at the respective proximal end of the arm for attaching the connector 130 to an expansion tower or retractor. The

arms

152a, 152b can include or can be coupled to an extension or reduction tab (not shown) that extends proximally from the connector 130 to functionally extend the length of the

arms

152a, 152 b. The extension tabs may facilitate insertion and reduction of a rod or other implant and insertion and locking of the second set screw 134. The extension tabs may be configured to disengage or otherwise disengage from the

arms

152a, 152 b. An inner surface of each of the

arms

152a, 152b may be configured to mate with the second set screw 134. For example, the inner surfaces of the

arms

152a, 152b may include threads corresponding to external threads formed on the second set screw 134. Thus, rotation of the second set screw 134 relative to the connector 130 about the axis A2 may effectively translate the set screw axially along the axis A2 relative to the connector.

A proximal opening 152p of the second rod receiving groove 152 may be formed in a proximal facing surface 150p of the second portion 150 of the connector. The secondary rod 107 may be inserted through the proximal-most opening 152p of the groove 152 and advanced distally and laterally toward the distal-most seat 152d of the groove 152. Forming the second rod receiving recess 152 so that it is open in the proximal direction as shown can advantageously allow the rod 107 to be top loaded into the connector 130, which is typically the case with other bone anchor assemblies in which larger constructs of the rod 107 are to be inserted. By matching the orientations, insertion and repositioning of the stem 107 may be facilitated.

The second rod receiving groove 152 may be curved or angled. For example, the groove 152 may be a curved U-shaped channel, as shown. The groove 152 may be curved or angled in the plane defined by axes A5 and A2. Thus, the most proximal opening 152p of the groove 152 may be laterally offset relative to the most distal seat 152d of the groove in a direction perpendicular to the axis A2 and perpendicular to the axis A4. The degree of this offset may be selected to achieve a desired center-to-center offset of the first rod 106 and the second rod 107. In some embodiments, the connector 130 may be configured such that the center-to-center offset of the first and

second rods

106, 107 is in the range of about 6.0mm to about 10.0 mm. In some embodiments, the connector 130 may be configured such that the center-to-center offset of the first and

second bars

106, 107 is about 8.0mm. The ratio of center-to-center offset to diameter of the first and

second rods

106, 107 may be in the range of 1. In some embodiments, the ratio of the center-to-center offset to the diameter of the first and

second rods

106, 107 may be about 2. It may be advantageous to reduce the center-to-center offset of the first and

second rods

106, 107. For example, a small offset may facilitate the use of a connector at or near the transition from the cervical to thoracic vertebrae. In this region, the trajectory of the bone anchor is typically switched from medial-lateral to lateral-medial of the cervical spine to lateral-medial of the thoracic spine, resulting in the bone anchor heads being laterally offset from one another, but still in close proximity. Small offset connectors can allow rods disposed in these bone anchors to couple to one another without taking up a significant amount of space or jumping over vertebral levels when attaching the bone anchors to the spine.

The offset between the proximal end 152p and the distal end 152d of the groove 152 may be achieved by bending the groove. The path of the curved groove 152 may extend along a radius of curvature about an axis parallel to axis A4. In some embodiments, the radius of curvature may range from about 5.0mm to about 10.0 mm. In some embodiments, the radius of curvature may be about 7.5mm.

Alternatively, the offset between the proximal end 152p and the distal end 152d of the groove 152 may be achieved by angling the groove. For example, the walls of the groove 152 may extend at an oblique angle relative to the axis A5 of the connector 130. In some embodiments, the walls of the groove 152 may extend at an angle in the range of about 10 degrees to about 20 degrees relative to the axis A5. In some embodiments, the walls of the groove 152 may extend at an angle of about 15 degrees relative to the axis A5.

In the illustrated embodiment, when the assembly 100 is implanted in a patient, the central axis A3 of the first rod 106 and the central axis A4 of the second rod 107 lie in the same coronal plane such that the first rod 106 and the second rod 107 overlap in a sagittal view. In other embodiments, the

rods

106, 107 may be non-overlapping in the sagittal view, for example, as discussed below with respect to fig. 8-9C. For example, the second rod 107 may be disposed before the first rod 106 or disposed after the first rod 106.

In the illustrated embodiment, the central axis A3 of the first rod 106 and the central axis A4 of the second rod 107 are parallel to each other. In other embodiments, the connector 130 may be configured such that the central axis A3 of the first stem 106 is angled perpendicularly or obliquely with respect to the central axis A4 of the second stem 107.

As shown in fig. 1C and 1D, the connector 130 may include a threaded recess 156 defined by the first and

second arms

152a, 152b for receiving the second set screw 134. The set screw groove 156 may be generally circular and may have a center that is laterally offset from a center of the proximal opening 152p of the second rod receiving groove 152. The set screw groove 156 may include threads 156a formed on the first arm 152a and threads 156b formed on the second arm 152 b. In the illustrated embodiment, the set screw 134 bears directly against the second rod 107, which second rod 107 in turn bears directly against the rod seat 152d in the distal end of the second rod receiving channel 152. However, it should be understood that one or more intermediate elements may also be included. The set screw 134 may include a drive interface (e.g., star, flat, cross-head, square, or other) to facilitate rotational advancement or retraction of the set screw relative to the connector 130 using a drive instrument. As shown in fig. 1D, the extent to which the set screw groove 156 extends into the

arms

152a, 152b may vary between the first arm 152a and the second arm 152 b. Thus, when the rod 107 is seated against the distal extension 152d of the second rod receiving groove 152, the set screw axis A2 may be laterally offset from the central axis A4 of the rod 107. In other words, the connector 130 may be configured such that the set screw axis A2 does not intersect the second rod axis A4.

Thus, the set screw 134 is offset from the secondary rod 107 by bending or angling the rod-receiving groove 152, by displacing the set screw groove 156 relative to the rod-receiving groove 152, or by a combination of both techniques, as shown in fig. 1D. By offsetting the set screw 134 from the second rod 107, the center-to-center offset between the first and

second rods

106, 107 may be reduced while maintaining sufficient material in the

arms

152a, 152b to securely fasten the set screw 134. Thus, optimal or desired rod placement can be achieved without compromising the structural integrity of the construct under heavy anatomical loads encountered in the spine.

In the above description, the connector 130 is secured to the receiver member 104 using the cylindrical set screw 108 and the nut 132. It should be understood that other mechanisms may be used to attach the connector 130 to the receiver member 104. For example, fig. 2A-2E illustrate an example connector assembly 200 that includes a locking spherical articulation joint. The structure and operation of the connector assembly 200 is substantially identical to that of the bone anchor assembly 100 described above, except as described below or as will be readily understood by those of ordinary skill in the art.

As shown, the opening 242 in the connector 230 may include an inner articulation surface 247. While the inner surface 247 can have a variety of geometries, the illustrated surface 247 is spherical, e.g., defined by a portion of a sphere. The assembly 200 may include a lock nut 260 configured to be received within the opening 242 of the connector 230. The locking nut 260 may include an outer articulation surface 249. While the outer surface 249 may have a variety of geometries, the illustrated surface 249 is spherical, e.g., defined by a portion of a sphere. The inner surface 247 and the outer surface 249 may be complementary such that the lock nut 260 is polyaxially movable within the opening 242 relative to the connector 230. In some embodiments, surfaces 247, 249 can have the same radius of curvature.

The locking nut 260 may be configured to expand and/or contract in a radial direction. For example, lock nut 260 may include one or more slits 266 formed therein, where lock nut 260 may deform to radially expand or contract at the one or more slits 266. The illustrated locking nut 260 includes first and second diametrically opposed slots 266p formed in a proximal surface 260p thereof and first and second diametrically opposed slots 266d formed in a distal surface 260d thereof, although it should be understood that the locking nut 260 may include any number of slots formed in a proximal surface, a distal surface, or both. The slots 266p formed in the proximal surface 260p may be angularly offset relative to the slots 266d formed in the distal surface 260d around the circumference of the lock nut 260. For example, a 90 degree offset may be used as shown. A slot 266p formed in proximal surface 260p may serve as a drive feature to receive a drive instrument for rotating lock nut 260 about set screw 208 to further threadably connect lock nut 260 to set screw 208.

The lock nut 260 may include a threaded through bore 262, such as shown in fig. 2C, for threading the lock nut 260 onto the set screw 208. The threads of the through-hole 262 and the threads of the set screw 208 may cooperate to cause radial expansion of the lock nut 260 when the lock nut is rotated in a first direction relative to the set screw and radial contraction of the lock nut when the lock nut is rotated in a second, opposite direction relative to the set screw. For example, the threads of set screw 208 may be cylindrical and the threads of lock nut 260 may be tapered or tapered. As another example, the threads of the set screw 208 may be tapered or tapered, and the threads of the lock nut 260 may be cylindrical. The tapered threads may taper at an angle of about 2 degrees to about 10 degrees from the axis of rotation of the lock nut 260. The tapered threads may taper at an angle of about 5 degrees to about 10 degrees from the axis of rotation of lock nut 260. The threads may have a tapered major diameter, a tapered minor diameter, or both.

In use, as discussed above, a set screw 208 may be disposed in the receiver member 204 of the bone anchor assembly 201 to secure a first rod (not shown) within the bone anchor assembly. For example, after securing the first rod within the receiver member 204, the connector 230 may be located on the proximal end 208p of the set screw 208. A lock nut 260 may be received within the connector opening 242 and threaded at least partially onto the set screw 208 to retain the connector 230 on the set screw. The assembly 200 may have a first, unlocked configuration in which the lock nut 260 is not tightened on the set screw 208 and is in a radially contracted state to allow polyaxial movement of the connector 230 relative to the lock nut 260 and thus relative to the receiver member 204. The assembly 200 may also have a second locked configuration in which the lock nut 260 is tightened onto the set screw 208 and is in a radially expanded state to press against an inner surface 247 of the opening 242 formed in the connector 230 to lock the connector 230 for polyaxial movement relative to the lock nut 260 and thus relative to the receiver member 204. The assembly 200 may also have an intermediate state in which the locking nut 260 is partially tightened so that a drag force is applied to the connector 230, for example, to allow temporary positioning of the connector to be maintained while still allowing movement when desired by the user.

As shown in fig. 2D, in the unlocked configuration, lock nut 260 may have a maximum outer diameter D1 sized to allow connector 230 to polyaxially rotate about lock nut 260. As shown in phantom in fig. 2D, in the locked configuration, lock nut 260 may have a maximum outer diameter D2 that is greater than unlocked diameter D1. Thus, tightening the locking nut 260 onto the set screw 208 effectively creates a compression fit between the connector 230 and the locking nut to lock the orientation of the connector relative to the receiver member 204. The locking nut 260 may be formed from any of a variety of known materials suitable for selective expansion and contraction. Although slits 266 are shown, locking nut 260 may be formed from a mesh material, may include slits extending completely therethrough, or may be configured to expand and contract radially without breaking.

The spherical articulation joint of the assembly 200 may be used as a ball joint, allowing a range of articulation between the connector 230 and the receiver member 204. This may provide an additional degree of freedom in positioning the connector 230 relative to the first and second rods, which may be helpful when, for example, the first and second rods are not parallel in any plane. The assembly 200 may allow the locking and tightening functions of the articulation joint to be achieved in a single component, which may advantageously reduce the height distribution of the construct within the wound.

The distal surface of the connector 230 may be shaped to enhance the degree to which the connector 230 may be angled relative to the receiver member 204, or to limit movement of the connector relative to the receiver member in one or more directions, as described below with respect to fig. 3A-3D.

The replacement articulation joint is shown in fig. 3A-3D. For clarity, only the first portion 340 of the connector 330 is shown in fig. 3A-3D. It will be appreciated that in practice, the connector 330 will also include a second portion of the type described herein for receiving a second rod. The articulation joint of fig. 3A-3D is substantially the same as the articulation joint of fig. 2E of fig. 2A, except as described below.

As shown, the locking nut 360 may have a truncated spherical shape with a proximal surface 360p and a distal surface 360d. The lock nut 360 may be sized and shaped to be polyaxially received within the opening 342 of the connector 330 to allow polyaxial movement of the connector 330 relative to the receiver member 304. The lock nut 360 may include a cut or slit 366 extending from the proximal surface 360p to the distal surface 360d and radially inward from an outer surface of the lock nut to the threaded throughbore 362. The slits 366 may allow the locking nut 360 to radially expand or contract.

The lock nut 360 may include a slotted drive feature defined by a plurality of protrusions 368 extending proximally from a proximal-facing surface 360p of the lock nut. Each protrusion may include a first abutment surface 369a and a second abutment surface 369b.

Abutment surfaces

369a, 369b may allow for bi-directional application of torque to lock nut 360 using a driving instrument. As shown in fig. 3C, first abutment surface 369a, second abutment surface 369b, or both may be shaped to prevent binding with a driving instrument as lock nut 360 is extended and retracted. For example, the

surfaces

369a, 369b may be convexly curved or may have rounded corners where these surfaces intersect the outer surface of the lock nut 360. As the lock nut 360 contracts during extension or loosening during tightening, the dimensions of the slotted drive feature likewise expand and contract. By rounding the

surfaces

369a, 369b, relief is provided to allow release of the driving instrument and to prevent binding or clamping of the driving instrument during such expansion or contraction.

The distal surface 340d of the connector 330 can be shaped to enhance the degree to which the connector can be angled relative to the receiver member 304, or to limit movement of the connector relative to the receiver member in one or more directions. For example, as shown in fig. 3D, the distal surface 340D of the connector 330 can include a first generally planar region 370 and a second generally planar region 371 extending obliquely from the first region. When positioned as shown in fig. 3D, the first planar region 370 abuts a proximally facing surface of the receiver member 304 to prevent pivotal movement of the connector 330 in a direction perpendicular to the first rod 306. However, the angled second portion 371 provides clearance between the distal surface 340d of the connector 330 and the proximal surface of the receiver member 304, thereby allowing pivotal movement of the connector in a direction parallel to the lever 306. It should be understood that in other embodiments, the distal surface 340d of the connector 330 may be configured to allow pivoting perpendicular to the rod 306 and prevent pivoting parallel to the rod, or otherwise restrict the connector from moving relative to the receiver member 304.

The outer surface of the locking nut 360 may be shaped to enhance the degree to which the connector 330 may be angled relative to the receiver member 304, or to limit movement of the connector relative to the receiver member in one or more directions. For example, the outer surface may include one or more protrusions (not shown) formed thereon that interfere with movement of the connector 330 about the lock nut 360. The position of the one or more protrusions may be selected to limit movement of the connector in a desired direction or to a desired degree.

The connector assemblies herein may include various features for allowing or preventing certain movement of the connector relative to the receiver member.

For example, as shown in fig. 4A-4B, the connector 430 may mate with the receiver member 404 via a gimbal interface. The first portion 440 of the connector 430 may have a dome-shaped or spherical distal-facing surface 404d that is configured to slide against and across a corresponding dome-shaped or spherical proximal surface of the receiver member 404. As shown in fig. 4B, this may allow the connector 430 to polyaxially move on the receiver member 404 such that the central axis A5 of the connector opening 442 is obliquely angled relative to the central axis A1 of the receiver member 404. The connector opening 442 may be oversized relative to the set screw to allow relative movement between the connector 404 and the receiver member 430 when the connector is disposed on the set screw. The opening 442 may be oversized in all directions, for example, by forming an opening having a diameter larger than the diameter of the set screw received therein. The opening 442 may also be oversized in only certain defined directions to limit movement of the connector 430 relative to the receiver member 404. For example, the openings 442 may be formed as elongated slots, as shown in fig. 4C. The slot may be elongated in a direction parallel to the second bar 407 as shown, in a direction perpendicular to the second bar, or in any other desired direction. Although the oversized or elongated opening 442 is described herein in connection with a gimbal interface, it should be understood that the opening may be oversized, elongated, etc., even in embodiments that do not include a gimbal interface. When the connector 430 is positioned as desired, the nut may be tightened to lock the connector at the desired position relative to the receiver member 404. The distal contact surface of the nut may be concave to form a negative of or otherwise mate with the proximal surface 440p of the connector 430. The gimbal interface may allow for an angular offset α between axis A1 and axis A5. The geometry of the connector opening 442 and set screw received therein may be selected to limit the maximum angle of the connector relative to the receiver member 404. In some embodiments, the maximum angle may range from about 2.5 degrees to about 45 degrees in any direction. In some embodiments, the maximum angle may be about 7.5 degrees in any direction.

As another example, the distal end of the first portion of the connector may be configured to limit movement of the connector relative to the receiver member. As shown in fig. 5A-5B, the sidewall 545 of the first portion 540 of the connector 530 may have one or more flats 572 formed therein that cooperate with corresponding flats formed on the outer surface of the receiver member to limit or prevent rotation of the connector relative to the receiver member about the axis A1. Side wall 545 may be open at one or both ends of connector 530, and opening 542 may be elongated to allow connector to pivot in a uni-planar manner about axis A6 relative to receiver member. Such an arrangement may be used, for example, when a user wishes to ensure that the first and second rods are parallel but desires flexibility for adjusting the relative proximal-distal height or center-to-center offset between the rods. As shown in fig. 5C, the distal-facing surface 540d of the connector 530 may have a groove 544' formed therein that forms a negative of the proximal end of the receiver member. Thus, when the proximal end of the receiver member is received within the recess 544', the connector 530 cannot rotate or translate relative to the receiver member. Such an arrangement may be used, for example, when a user wishes to ensure that the first and second rods are parallel and disposed at a predetermined proximal-distal height relative to each other and at a predetermined center-to-center offset relative to each other.

As yet another example, the distal end of the first portion of the connector may include a locator configured to selectively limit rotation of the connector relative to the receiver member about axis A1. As shown in fig. 6A-6D, the locator 660 may be disposed between the first portion 640 of the connector 630 and the receiver member 604. The positioner 660 may generally include an annular body 662 and

anti-rotation features

664a, 664b. The annular body 662 may have a central opening 663 and proximal and

distal surfaces

662p, 662d. Proximal surface 662p can include surface features 666 (e.g., teeth, star grinders (star grinders), etc.). Distal surface 662d can include anti-rotation features such as spaced apart

tabs

664a, 664b projecting distally therefrom. The

tabs

664a, 664b may be spaced apart to define a groove 665 therebetween for receiving the

respective arms

604a, 604b of the receiver member 604. The width of the

tabs

664a, 664b may be substantially the same as the width of the groove 620 defined by the

arms

604a, 604b of the receiver member.

Tabs

664a, 664b may include a lip 668, with lip 668 projecting radially from the tab to help retain locator 660 within connector 630, as described further below.

As shown in fig. 6B, the first portion 640 of the connector 630 may include a recess 644 configured to receive the locator 660. Groove 644 may include a distal-facing surface 644d that includes surface features 646 (e.g., teeth, star grinders, etc.). Distal-facing surface 644d may be configured such that surface features 646 selectively bear against surface features 666 of proximal-facing surface 662p of positioner 660 when the build body is tightened. The recess 644 may include an annular slot 648 in a sidewall 645 of the recess. Annular slot 646 can be sized and shaped to receive complementary lips 668 formed on

tabs

664a, 664b of retainer 660 to retain retainer 660 within groove 644. Alternatively, the connector 630 and the retainer 660 may be held together by swaging, snap fit, threading, and other techniques. The connector 630 and the retainer 660 may form a subassembly that may be mounted as a single component to the set screw 608. Alternatively, the connector 630 and the retainer 660 may be discrete components that are individually mounted to the set screw 608 one at a time.

The locator 660 and connector 630 may be mounted over the set screw 608 to rest on top of the receiver member 604. When the set screw 608 is placed through the central opening 663 of the retainer 660, the retainer 660 may be rotated about the set screw 608 to position the

tabs

664a, 664b above the stem 606 between the

arms

604a, 604b of the receiver member 604 and to position the

arms

604a, 604b in the groove 665 of the retainer 660. When the

tabs

664a, 664b are disposed between the

arms

604a, 604b of the receiver member 604, the tabs may abut one another. In this configuration, the assembly 600 may prevent relative rotation between the locator 660 and the receiver member 604 due to the

protrusions

664a, 664b abutting the

arms

604a, 604 b.

The connector 630 and the retainer 660 are selectively rotatable relative to one another about axis A1 before the nut or other securing mechanism 632 has been tightened to compress the assembly 600 together. When fastening mechanism 632 is tightened, surface features 646, 666 on both the distal-facing surface of groove 644 and proximal surface 662p of positioner 660 may interact to selectively resist or prevent such rotation. The features of the connector 630 and the locator 660 can be shaped such that they are complementary to each other and can be received within each other, as shown in fig. 6B. The interaction between the surface features 646, 666 may, for example, eliminate the need for a counter torque instrument when securing the connector 630 on the receiver member 604, e.g., when tightening the first set screw, the second set screw, or the nut. When surface features 646 of connector 630 engage or fit within surface features 666 of locator 660, surface features 646, 666 may resist or prevent relative rotation about axis A1.

Fig. 7A-7L illustrate another connector assembly 700 including a connector 730 and a retainer 760. The structure and operation of the connector assembly 700 is substantially identical to that of the bone anchor assembly 600 described above, except as described below or as will be readily understood by those of ordinary skill in the art. As shown in fig. 7A-7B, the positioner 760 may be configured to selectively restrict rotation of the connector 730 relative to the receiver member 704 about the axis A1. The locator 760 may be disposed between the first portion 740 of the connector 730 and the receiver member 704.

As shown in fig. 7C-7F, the positioner 760 may generally include an annular body 762. The ring body 762 may include a central opening 763, proximal and

distal surfaces

762p, 762d, and an outer sidewall 762s. The body 762 may include a first hemisphere or portion 767a and a second hemisphere or portion 767b.

The positioner 760 may include anti-rotation features configured to interact with the receiver member 704 to limit or prevent rotation between the positioner 760 and the receiver member 704 about the axis A1. For example, the positioner 760 may include spaced apart

tabs

764a, 764b projecting distally therefrom. The

tabs

764a, 764b may be spaced apart to define a groove 765 therebetween for receiving the

respective arms

704a, 704b of the receiver member 704. The width of the

tabs

764a, 764b may be substantially the same as the width of the channel 720 defined by the

arms

704a, 704b of the receiver member 704. When inserted between the

arms

704a, 704b of the receiver member 704, the

tabs

764a, 764b may prevent the positioner 760 from rotating about the axis A1 relative to the receiver member 704.

Each

tab

764a, 764b may include a first lip 768a that protrudes radially outward from the tab to help retain the retainer 760 within the connector 730, as described further below. First lip 768a can have a sloped, curved, or otherwise tapered proximally facing lead-in surface that facilitates assembly with connector 730. In particular, the tapered surface may allow the first lip 768a to ride over the flange 725 of the connector 730 and snap fit into the slot 748 formed in the connector 730.

Each

tab

764a, 764b may include a second lip 768b that projects radially outward from the tab to engage the connector 730 during tightening to clamp the retainer 760 to the set screw 708, as described further below. The second lip 768b can have a proximal-facing bearing surface that is sloped, curved, or otherwise tapered. In some embodiments, the inclined surface of the second lip 768b can extend at an angle in the range of about 30 degrees to about 60 degrees from horizontal. In some embodiments, the inclined surface of the second lip 768b can extend at an angle of about 45 degrees from horizontal.

A notch or other relief 769 may be formed at the junction between the tab 764 and the body 762 to facilitate the tabs deflecting or bending toward and/or away from each other, for example, during snap-fitting into the connector 730 or during clamping onto the set screw 708.

The retainer 760 may include features for selectively locking rotation between the retainer and the connector 730 about the axis A1. For example, the body 762 may include one or more teeth 766 protruding radially outward therefrom. The teeth 766 can engage or mesh with corresponding teeth 729 formed in the connector 730 to lock rotation between the retainer 760 and the connector. While three teeth 766 are shown, it should be understood that the body 762 may include any number of teeth, or the teeth may be omitted entirely. The teeth 766 may be formed only in the first portion 767a of the body 762 as shown, or may be formed at any location around the circumference of the body. The surfaces of the teeth 766 that contact and bear against the teeth of the connector 730 may be rounded, chamfered, or otherwise shaped to facilitate release of the retainer 760 from the connector 730. This may advantageously help mobilize the construct when the assembly is loosened (e.g., repositioning the construct prior to final tightening).

As another example, the body 762 can include one or more flats 723 formed in the outer sidewalls 762s of the body. In addition to the teeth 766 and/or one or more flats 723, the outer sidewall 762s can also be cylindrical. The flats 723 may engage or bear against corresponding flats 727 formed in the side walls 745 of the connector 730 to lock rotation between the retainer 760 and the connector. The flat 723 may be formed only in the second portion 767b of the body 762 as shown, or may be formed at any position around the circumference of the body. While a flat surface is shown, it should be understood that the positioner 760 may include other eccentric features, such as lobes, teeth, etc., that perform a similar function.

In some embodiments, the first portion 767a and the second portion 767b of the body 762 can each include teeth 766. In some embodiments, the first portion 767a and the second portion 767b of the body 762 can each include a flat 723. In some embodiments, the first portion 767a of the body 762 can include teeth 766 and the second portion 767b of the body can include a flat 723. In this arrangement, the locator 760 can be oriented in the connector 730 such that the second portion 767b is adjacent or proximate to the connector's lever slot. In some cases, to achieve the desired center-to-center offset of the first and second bars, the material thickness of the connector 730 adjacent the bar slots of the connector may be limited such that the use of teeth 766 in this area is impractical. Accordingly, flats 723 may be used in place of teeth on the second portion 767b of the retainer 760, such that the retainer 760 still includes anti-rotation features on both the first and

second portions

767a, 767b, even when the material thickness of the connector is limited.

The connector 730 is shown in more detail in fig. 7G and 7H. The connector 730 may include a first portion 740 for mating the connector with the bone anchor assembly 701 and a second portion 750 for mating the connector with a fixation element, such as an elongated spinal rod. The illustrated second portion 750 is exemplary, and the connector 730 may include any of the second portions described herein. The first portion 740 of the connector 730 may include a recess 744 configured to receive the retainer 760. The recess 744 may be at least partially defined by a sidewall 745. The slot 748 may be formed in the side wall 745 and may define the distal flange 725. The groove 748 can be sized and shaped to receive the first lip 768a of the retainer 760 to retain the retainer within the groove 744. The flange 725 may define a sloped, curved, or otherwise tapered distally facing lead-in surface. In some embodiments, the inclined surface of flange 725 may extend at an angle in the range of about 30 degrees to about 60 degrees from horizontal. In some embodiments, the inclined surface of the flange 725 may extend at an angle of about 45 degrees from horizontal.

As the retainer 760 is advanced proximally into the connector 730, the tapered proximal-facing surface of the first lip 768a can ride the tapered distal-facing surface of the compression flange 725 to deflect the arms 764 of the retainer inwardly until the retainer is advanced more proximally and the first lip 768a snap-fits into the slot 748. First lip 768a can be configured to slide within slot 748 such that retainer 760 can rotate within connector 730 prior to tightening assembly 700. The degree to which retainer 760 can be rotated within connector 730 prior to tightening can be limited. For example, as shown, the slot 748 may extend along less than the entire inner circumference of the sidewall 745. The illustrated slot 748 terminates at or near the 11 o 'clock position and the 1 o' clock position in fig. 7H. The ends of the slot 748 may define stop surfaces configured to contact the first lip 768a to limit rotation of the retainer 760 within the connector 730. The slot 748 can have a height along the axis A1 that is greater than a corresponding height of the lip 768a such that a limited amount of axial travel of the positioner 760 along the axis A1 relative to the connector 730 is permitted before the assembly 700 is tightened.

While a snap-fit arrangement is shown, alternatively, the connector 730 and the retainer 760 may be held together by swaging, snapping, screwing, and other techniques. The connector 730 and the retainer 760 may form a subassembly that may be mounted to the set screw 708 as a single component. Alternatively, the connector 730 and the retainer 760 may be separate components that are individually mounted to the set screw 708 one at a time.

Connector 730 may include features for engaging or otherwise interacting with teeth 766 and/or flats 723 of retainer 760. For example, the inner sidewall 745 of the connector 730 may include one or more flats 727 configured to mate with the flats 723 of the retainer 760. While a single flat 727 is shown in fig. 7H at the 12 o' clock position, it should be understood that the connector 730 may include any number of flats 723 at any of a variety of positions along the sidewall 745. As another example, the inner sidewall can include one or more teeth 729 configured to mate with teeth 766 of retainer 760. The teeth 729 can project radially inward from the sidewall 745. The teeth 729 can engage or mesh with corresponding teeth 766 of the retainer 760 to lock rotation between the retainer 760 and the connector 730. While four teeth 729 are shown, it is understood that the connector 730 may include any number of teeth, or the teeth may be omitted entirely. The surfaces of the teeth 729 that contact and bear against the teeth 766 of the retainer 760 may be rounded, chamfered, or otherwise shaped to facilitate release of the retainer 760 from the connector 730. This may advantageously help mobilize the construct when the assembly is loosened (e.g., repositioning the construct prior to final tightening). Such surface features may also facilitate alignment of the

teeth

766, 729 as the build body is tightened.

The retainer 760 and connector 730 may be mounted over the set screw 708 to rest on top of the receiver member 704. When the set screw 708 is placed through the central opening 763 of the retainer 760, the retainer 760 may be rotated about the set screw 708 to position the

tabs

764a, 764b above the rod 706 between the

arms

704a, 704b of the receiver member 704 and to position the

arms

704a, 704b in the grooves 765 of the retainer 760. When the

tabs

764a, 764b are disposed between the

arms

704a, 704b of the receiver member 704, the tabs may abut each other. In this configuration, the assembly 700 may prevent relative rotation between the positioner 760 and the receiver member 704 due to the

tabs

764a, 764b abutting the

arms

704a, 704 b.

The connector 730 and the retainer 760 may be rotated relative to each other about axis A1 before the nut or other securing mechanism 732 has been tightened to compress the assembly 700 together. When the securing mechanism 732 is tightened, the

teeth

766, 729 may engage to resist or prevent such rotation. The

flats

723, 727 may likewise engage each other as the nut 732 is tightened to provide further resistance to rotation between the connector 730 and the retainer 760. As shown in fig. 7I-7K, the interaction between the

teeth

729, 766 and the interaction between the

flats

723, 727 can allow the positioner 760 to be placed and locked in any of a plurality of discrete rotational positions relative to the connector 730. Thus, by extension, the connector 730 can be placed and locked in any of a plurality of discrete rotational positions relative to the receiver member 704. As mentioned above, in some embodiments, the assembly may include only teeth, only flats, or neither teeth nor flats. In the latter arrangement, when the nut 732 is tightened, locking may be achieved by frictional engagement between a proximal surface of the locator and a distal surface of the connector. In this arrangement, the positioner may be positioned in any of an infinite number of rotational positions relative to the connector.

As shown in fig. 7L, when the nut 732 is tightened, the connector 730 may move distally along the set screw 708 toward the receiver member 704. The positioner 760 may be prevented from advancing distally due to limited interference from at least one of the set screw 708, the receiver member 704, and the rod 706. As the connector 730 is advanced distally along the screw 708 relative to the retainer 760, the angled distally-facing surface of the flange 725 can bear against the angled proximally-facing surface of the second lip 768b of the retainer 760. This may cause the tabs 764 of the locators 760 to deflect radially inward and clamp onto the set screw 708. This clamping engagement between the retainer 760 and the set screw 708 may enhance the overall assembly and reduce or eliminate any play or toggling between the components. The tabs 764 may engage non-threaded portions of the set screw 708, such as one or more flats formed in a sidewall of the set screw. The tab 764 may include an arcuate relief or cut-out 731 (e.g., as shown in fig. 7F) to provide release of the threads of the set screw 708 and to help ensure that the arm 764 clamps only to the unthreaded and/or flat portion of the set screw.

Assembly 700 may include features to help ensure a consistent and effective tightening torque when tightening nut 732. For example, as shown in fig. 7L, the proximal surface of the connector 730 may include a raised projection 733. The projection 733 may define a proximally facing contact surface, which may be sloped, curved, or otherwise tapered. In the illustrated embodiment, the protrusions 733 define a male tapered surface. The nut 732 may include a complementary distally facing contact surface 735 that may be beveled, curved, or otherwise tapered. In the illustrated embodiment, the contact surface 735 of the nut 732 defines a female tapered surface. It should be understood that in other arrangements, the connector 730 may include a female surface and the nut 732 may include a male surface. The angles of the respective contact surfaces may be the same or may be different. For example, when viewed in cross-section, the distal-facing surface of the nut 732 can extend at an angle of about 30 degrees from horizontal, and the proximal-facing surface of the projection 733 can extend at an angle of about 35 degrees from horizontal. When the nut 732 and the projection 733 define different angles as shown, friction between the two mating surfaces may be from inside to outside in a radial direction away from the set screw axis when the build body is tightened. This may help to ensure a controlled, even increase in friction when tightening the nut, resulting in a consistent and effective tightening torque. Any of the connector assemblies disclosed herein may include this type of feature.

The connector assembly may include various features for positioning the second rod at a desired proximal-distal height relative to the first rod.

For example, as shown in fig. 8, the second rod receiving groove 852 may be elongated in a proximal-distal direction to allow the second rod 807 to be positioned distal of the first rod 806. In other words, the connector 830 may be used to position the second rod 807 in front of the first rod 806 when the assembly is attached to the patient's spine. As shown, the second rod receiving recess 852 may extend to a distal-most rod seat 852d that is further than the rod seat 820d of the first rod receiving recess 820.

As yet another example, as shown in fig. 9A-9C, the connector 930 may be configured to position the second rod 907 proximal to the first rod 906. In other words, the connector 930 may be used to position the second rod 907 behind the first rod 906 when the assembly is attached to the posterior aspect of the patient's spine. As shown, first and

second arms

952a, 952b of connector 930 may extend proximally over proximal surface 940p of first portion 940 of the connector to define a second rod receiving groove 952 having a rod seat 952d proximal of rod seat 920d of receiver member 904. While second stem receiving groove 952 is shown as straight, it should be understood that the groove may be curved or angled as described above.

Each of the

arms

952a, 952b may include features (not shown) such as grooves, dimples, notches, protrusions, etc. to facilitate coupling the connector 930 to various instruments. For example, the outer surface of each

arm

952a, 952b may include

arcuate slots

954a, 954b at the respective proximal ends of the arms for attaching the connector 930 to an extension tower or retractor.

Arms

952a, 952b may include or may be coupled to extension or reduction tabs (not shown) extending proximally from connector 930 to functionally extend the length of

arms

952a, 952 b. The extension tabs may facilitate insertion and reduction of a rod or other implant and insertion and locking of the second set screw 934. The extension tabs may be configured to disengage or otherwise separate from

arms

952a, 952 b.

The connector assembly may include various features for receiving the second rod.

For example, as shown in FIG. 10A, the second rod-receiving groove 1052 may have straight sidewalls rather than curved sidewalls. The second rod receiving groove 1052 may have a central axis A7 that is obliquely angled relative to the central axis A5 of the connector opening 1042. The

arms

1052a, 1052b of the connector 1030 may define a proximal face 1050p that lies substantially in a plane perpendicular to the axis A7 and at an oblique angle relative to the proximal face 1040p of the first portion 1040 of the connector 1030. In the connector 1030 shown in fig. 10A, the set screw is not offset from the second rod, but has an axis of rotation that intersects the central longitudinal axis A4 of the second rod. However, the angled groove 1052 still allows the second rod to be positioned in the second seat 1052d with a tight center-to-center offset relative to the first rod received in the receiver member.

As yet another example, as shown in fig. 10B, the second rod seat 1052d may be defined by one or more sloped or tapered surfaces. In the illustrated embodiment, the second rod seat 1052d is V-shaped with opposing flat surfaces 1073 that converge toward each other in the distal direction. A connector having such a geometry may advantageously allow second rods of various diameters to be securely locked within groove 1052.

As described above, the various connector features disclosed herein are interchangeable in various embodiments and can be used in any combination. Any combination of features disclosed herein is considered to be within the scope of the present disclosure. Any connector herein may have a second rod groove that is curved, angled, or straight. Any of the connectors herein can have a U-shaped second rod groove or a V-shaped second rod groove. Any of the connectors herein can be configured to position the second rod proximal to the first rod, distal to the first rod, or in proximal-distal alignment with the first rod. Any of the connectors herein may include a ball articulation joint, a gimbal interface, an elongated connector opening, a single plane groove, or a complete locking groove. Any of the connectors herein can be configured for use with any of the positioners herein to selectively restrict rotation of the connector relative to the receiver member.

The following provides an exemplary method of using the connector assembly disclosed herein, but it should be understood that the connector assembly may be used in any of a variety of other methods.

In use, referring again to fig. 1E, the connector assembly 100 can be used to secure the first and

second rods

106, 107 at a surgical site within a patient. The bone anchor assembly 101 may be implanted into a bone (e.g., the first vertebra V1) of a patient via an open procedure or a minimally invasive procedure using known techniques.

The first spinal rod 106 may be inserted into the receiver member 104 of the bone anchor assembly 101 and locked in place by tightening the set screw 108. In some embodiments, the bone anchor assembly 101 may have been implanted in a previous procedure, and the procedure may be a revision procedure that adds the tandem rod 107 to the existing rod 106, in which case the existing set screw may be removed and replaced with a set screw 108 of the type described herein. In other embodiments, the bone anchor assembly 101 may be implanted as part of the same procedure as the tandem rod 107.

Before or after tightening set screw 108, connector 130 may be inserted over the set screw by inserting the set screw through opening 142 of the connector. The connector 130 may be temporarily held in place by loosely coupling the nut 132 to the set screw 108.

The second spinal rod 107 may be inserted into the second rod receiving groove 152 of the connector 130. The second rod 107 may be temporarily secured within the recess 152 by partially tightening the second set screw 134.

The connector 130, receiver member 104, and/or

rods

106, 107 may be manipulated by a user to position the construct as desired, for example, to achieve a desired correction. For example, the connector may pivot about a ball articulation joint or gimbal interface of the type described herein. When the desired positioning is achieved, the first and

second set screws

108 and 134 and the nut 132 may be tightened in any order to lock the construct. Specifically, first set screw 108 may be tightened to lock polyaxial movement of receiver member 104 relative to bone anchor portion 102 and to lock first rod 106 within receiver member 104. The second set screw 134 may be tightened to lock the second rod 107 within the connector 130. The nut 132 may be tightened to lock the relative position between the connector 130 and the receiver member 104.

First rod 106 and/or second rod 107 can be secured to the patient's spine using additional bone anchor assemblies, e.g., implanted in adjacent or nearby vertebrae, such as adjacent vertebra V2. The plurality of connector assemblies may be used to attach additional rods to the construct, or to secure the first and second rods to another vertebra at another location on their respective lengths.

The above method may be used to connect the first and second rods to the vertebrae using a single bone anchor. The above method may be used to connect a first rod and a second rod in series to achieve an offset between the first rod and the second rod, for example, for clearing patient anatomy or other implants.

The connector assemblies disclosed herein and their various component parts may be constructed of any of a variety of known materials. Exemplary materials include materials suitable for use in surgical applications including metals (such as stainless steel, titanium, nickel, cobalt chromium and combinations or alloys thereof), polymers (such as PEEK, ceramics, carbon fiber), and the like. The various components of the implants disclosed herein can be rigid or flexible. One or more components or portions of the implant may be formed of a radiopaque material to facilitate visualization under fluoroscopy and other imaging techniques, or of a radiolucent material so as not to interfere with visualization of other structures. Exemplary radiolucent materials include carbon fibers and high strength polymers.

The devices and methods disclosed herein may be used in minimally invasive surgery and/or open surgery. The devices disclosed herein may be fully or partially implanted, or may be used in external fixation systems. While the devices and methods disclosed herein are generally described in the context of the spine, it should be understood that the methods and devices disclosed herein may be used with any human or animal bone or other tissue in any of a variety of procedures performed on a human or animal and/or in areas not related to implants or procedures. Although connectors for coupling two rods are generally disclosed herein, in some embodiments, a connector may couple three or more rods to one another. As mentioned above, the connector assemblies disclosed herein are not limited to use with rods, but rather can be used to couple any of a variety of different types of orthopedic devices, such as wires, tethers, plates, and the like.

While specific embodiments have been described above, it should be understood that numerous changes could be made within the spirit and scope of the concepts described. Accordingly, it is intended that the disclosure not be limited to the described embodiments.

Claims

1. A connector assembly, the connector assembly comprising:

a connector having a proximal end and a distal end defining a proximal-distal axis, the connector comprising:

a first portion configured to mate the connector with a receiver member of a bone anchor assembly having a first rod-receiving recess for receiving a first rod, an

A second portion in which a second rod receiving groove is formed, the second rod receiving groove configured to receive a second rod;

a first fastener having a distal portion configured to engage the receiver member to lock the first rod to the receiver member and a proximal portion extending through an opening formed in the first portion of the connector;

a nut configured to mate with the first fastener to secure the connector to the receiver member; and

a second fastener engaged with the second portion of the connector to lock the second rod to the connector;

wherein the second rod receiving recess comprises a proximal opening and a distal seat, and wherein the proximal opening is offset from the distal seat in a direction perpendicular to the proximal-distal axis.

2. The assembly of claim 1, wherein the first and second housings are,

wherein the first rod and the second rod have a rod diameter,

wherein the first and second rods have a center-to-center offset when seated in the receiver member and the connector, respectively, and

wherein the ratio of the center-to-center offset to the rod diameter is in the range of 2.

3. The assembly of claim 1, wherein the center-to-center offset of the first and second rods is in the range of 6mm to 16mm when seated in the receiver member and the connector, respectively.

4. The assembly of claim 1, wherein the center-to-center offset of the first and second rods is 8mm when seated in the receiver member and the connector, respectively.

5. The assembly of claim 1, wherein the first rod receiving recess includes a first rod seat, and the first rod seat is distal to the seat of the second rod receiving recess.

6. The assembly of claim 1, wherein the first rod receiving recess includes a first rod seat, and the first rod seat is proximal to the seat of the second rod receiving recess.

7. The assembly of claim 1, wherein the first rod receiving recess comprises a first rod seat, and the first rod seat is at substantially the same proximal-distal height as the seat of the second rod receiving recess.

8. The assembly of claim 1, wherein the first portion of the connector includes a groove configured to receive a proximal end of the receiver member, the groove being cylindrical such that the receiver member is free to rotate relative to the connector about a central axis of the receiver member when the receiver member is received in the groove.

9. The assembly of claim 1, wherein the first portion of the connector comprises a groove configured to receive a proximal end of the receiver member, the groove comprising one or more flats that abut corresponding flats of the receiver member such that the receiver member is constrained to uniplanar movement relative to the connector when the receiver member is received in the groove.

10. The assembly of claim 1, wherein the first portion of the connector includes a groove configured to receive a proximal end of the receiver member, the groove forming a substantial negative of the receiver member such that the receiver member cannot rotate or translate relative to the connector when the receiver member is received in the groove.

11. The assembly of claim 1, wherein the first portion of the connector includes a dome-shaped distally facing surface that bears against a proximally facing surface of the receiver member in a gimbal interface.

12. The assembly of claim 1, wherein the opening in the first portion of the connector is oversized relative to the first fastener to allow movement of the connector relative to the receiver member.

13. The assembly of claim 1, further comprising:

a locator having a central opening that receives the first fastener therein and a distally extending tab that engages the receiver member to limit rotation between the locator and the receiver member.

14. The assembly of claim 13, wherein the locator includes teeth configured to selectively engage with the teeth of the connector to limit rotation between the connector and the receiver member.

15. The assembly of claim 13, wherein the retainer includes flats formed on an outer sidewall of the retainer and configured to selectively engage flats formed on an inner sidewall of the connector to limit rotation between the connector and the receiver member.

16. The assembly of claim 13, wherein tightening the nut is effective to clamp the tab of the locator to the first fastener.

17. The assembly of claim 1, wherein the nut has a spherical outer surface that is received within a spherical inner surface of the opening formed in the first portion of the connector to allow the connector to move coaxially with respect to the receiver member.

18. The assembly of claim 1, wherein the nut includes a distally facing tapered surface that contacts a proximally facing tapered surface of the connector.

19. The assembly of claim 18, wherein the tapered surfaces of the nut and the connector taper at different angles from one another.

20. The assembly of claim 1, wherein the nut is a locking nut configured to expand within the opening to lock an orientation of the connector relative to the receiver member.

21. The assembly of claim 20, wherein at least one of the first fastener and the through-hole of the lock nut has a tapered thread such that rotation of the lock nut relative to the first fastener is effective to radially expand the lock nut.

22. The assembly of claim 20, wherein the locking nut has a slotted drive feature with a curved abutment surface.

23. The assembly of claim 18, wherein a distal surface of the connector is configured to constrain movement of the connector relative to the receiver member to a direction parallel to the first rod.

24. The assembly of claim 18, wherein a distal surface of the connector is configured to constrain movement of the connector relative to the receiver member to a direction perpendicular to the first rod.

25. The assembly of claim 1, wherein the second rod is positionable in the second rod receiving recess by moving the second rod distally relative to the connector.

26. The assembly of claim 1, wherein the second rod receiving recess follows a curved path between the proximal opening and the distal socket.

27. The assembly of claim 1, wherein the second rod receiving recess follows a path that is obliquely angled relative to the proximal-distal axis of the connector.

28. The assembly of claim 1, wherein the axis of rotation of the second fastener does not intersect the central longitudinal axis of the second rod when the second rod is seated in the connector.

29. The assembly of claim 1, wherein an axis of rotation of the second fastener extends at an oblique angle relative to the proximal-distal axis of the connector.

30. The assembly of claim 1, wherein the second fastener is a set screw and is received within a set screw recess formed in the connector, a center of the set screw recess being offset from a center of the proximal opening of the second rod receiving recess in a direction perpendicular to the proximal-distal axis.

31. The assembly of claim 1, wherein the distal seat of the second rod receiving groove defines a V-shape configured to receive rods of different diameters.

32. The assembly of claim 1, further comprising the bone anchor assembly, the first rod, and the second rod.